So after reading the above posts I would like to contribute .
I have a machine core i5 processor not sure on which model and a DH87rl motherboard, I have 1 stick of memory in place and after numerous tests have decided to post my problem, I have tried two power supplies and various minimal configurations.
The machine will post and boot up and shut down when it is tasked to do so.
When I try a ctrl+Alt+Del, or windows reboot or even a bios alteration the machine will not post after the request.
Example in windows, click restart the machine will shutdown and go to a blank screen like power save, monitor will switch off and the machine wont post, if I switch off the machine holding power button for 3 seconds and then switch on the machine it will post and boot correctly .
Same happens if I do a bios change and save and exit the machine lights will be on, fans spinning, but wont boot, I have to cycle power and it will post correctly with no errors .
Same if I disconnect HDD and machine doesn't have a OS to boot into, the machine will come up with a boot error, pressing CTRL + ALT+DEL and the machine will go into power save or try and restart but the screen will be blank .
Using the latest bios version cant remember which one but I know its the latest compared version numbers I think 0320 .
Will await for your response this is a genuine conflict with processor haven't had a chance to try the i3 processor and see if it does the same .